Methods and apparatus for making concrete pile shells and piles



M. M. UPSON 3,034,304 METHODS AND APPARATUS FOR MAKING CONCRETE PILE SHELLS AND PILES May 15, 1962 6 Sheets-Sheet 1 Filed Dec. 29, 1958 INVENTOR. MXWELLM UPso/v.

I wwmamz fg m \hzukmb u uumnoh May 15, 1962 M. M. UPSON METHODS AND APPARATUS FOR MAKING CONCRETE PILE SHELLS AND PILES Filed Dec. 29, 1958 6 Sheets-Sheet} INVENTOR. g: I MAXWELL M UPSO/V.

Arm/ryc /i.

M y 15, 1 M. M. UPSON 3,034,304

METHODS AND APPARATUS FOR MAKING CONCRETE FILE SHELLS AND PILES Flled Dec 29 1958 6 Sheets-Sheet 4 IN VEN TOR.

MXWEL L M UPSO M.

MMMMZIMM UPSON METHODS AND APPARATUS FOR MAKING CONCRETE PILE SHELLS AND PILES 29, 1958 May 15, 1962 6 Sheets-Sheet 5 Filed Dec.

INVENTOR. MAX WELLM UPso/v.

BY fiS/F/VEVS. 7'

May 15, 1962 M. M. UPSON METHODS AND APPARATUS FOR MAKING CONCRETE PILE SHELLS AND FILES 6 Sheets-Sheet 6 Filed Dec. 29, 1958 INVENTOR.

Z%XWE1 1 M (/PSON.

HTTORNEVJ.

This invention relates to improved methods and apparatus for making cast-in-place concrete piles and, more particularly, such type piles wherein a protective shell formed of concrete is left in the ground.

This application is a continuation-in-part of applicants copending application Serial No. 558,261, filed January 10, 1956 and now abandoned entitled Methods and Apparatus for Making Concrete Pile Shells and Piles.

Cast-in-place concrete piles'of the type wherein a steel shell is left as driven in the ground and concrete poured therein have found widespread utility in the construction field. One of the prime reasons for the commercial success of this type pile lies in the fact that its method of assembly permits of inspection of the inside of the shell immediately prior to actually pouring the concrete therein, thereby insuring that the pile will be a perfect one. Moreover, by measuring the inches of penetration into the ground of such a metal shell during each of the final few hammer blows, the load bearing capacity of the pipe point can readily be determined (i.e., pre-tested) prior to the actual pouring of the concrete. Because of the cost and shortages of steel, attempts have been made for many years to devise a method of providing cast-inplace concrete piles which do not require such a steel shell. Thus the so-called shell-less type piles have been developed, wherein a temporary metal casing or shell is first driven into the ground and concrete then poured into the interior of the same, whereupon, before the setting of the concrete, the temporary casing or shell is pulled upwardly leaving a concrete pile without any protective shell. This method necessarilyinvolves certain disadvantages, since a very heavy upward pull must be exerted to remove the casing with the result often being an upward dislodgement of the pile point. Such upward movement of thepile point, however slight, is very damaging to the ultimate construction, since when such a pile is subsequently loaded its point will sink down on a corresponding distance, thereby causing a similar settling of the building or other load it supports. Efforts have been made by others to eliminate this defect by reacting the upward force used to pull the casing downward on the concrete which has been poured into that casing. This method, however, has not proven satisfactory in actual usage since this downward reactive force, when applied to the unset concrete, will cause that concrete to arch and distribute a substantial component of the downward force to the very casing one is trying to remove. Thus the casings upward removal will be resisted by a component of the pull reacting downwardly on that same casing. Indeed, experience has shown that with casings of the length herein contemplated (i.e., 20 to 50' or more), the resistance to removal thus set up will be so great as to prevent the casings withdrawal altogether. Moreover, the type of pile formed by these prior methods utilizing a temporary outer casing is subject to certain inherent disadvantages, especially when, as is usually the case, several piles are to be driven in closely adjacent positions, for although the same may initially be formed in good condition, as soon as driving of a closely adjacent pile commences, the lateral walls of this first shell-less pile are subjected to severe ground stresses, resulting in partial or complete distortion thereof. Experience has shown atent O thus providing a strong and durable shell.

3,034,364 Patented May 15, 1962 that when a plurality of piles are driven in closely adja-.

to secure a perfect form for the reception of the concrete has involved the use of the above-desicribed steel shell. Attempts have therefore been made to form cast-in-place concrete shells, and in such operations a prime difliculty has been one of pouring the mix in such fashion as to insure tight packing thereof and to eliminate air pockets, One suitable method of accomplishing such an objective was disclosed in US. Patent No. 2,421,666, issued June 3, 1947 to M.,

M. Upson, the applicant herein, and E. A. Smith.v

The instant invention in one of its aspects provides an improved method of forming cast-in-place concrete piles having concrete rather than metal shells wherein not only is the pile point prevented from any upward dislodgement during removal of the temporary outer casing but, moreover, the pile point is simultaneously pretested for load bearing capacity prior to the pouring of the concrete pile itself, thereby providing another of the vital advantages of metal pile shells, the same not being found in the above-described heretofore known methods of forming concrete piles by the use of a temporary metal casing. According to this aspect of the invention, a mandrel and surrounding spaced apart temporary casing, both seated on a boot or pile point, are driven into the ground and concrete poured therebetween. Then before the concrete has fully set, the casing is removed'by applying an upward pull thereto while delivering the corresponding downward reactive force directly to the pile point via the mandrel.

The invention in another of its aspects provides an improved method of forming castin-place concrete piles having shells wherein the concrete mix is in the wet or fluid condition during driving thereof. According to this aspect of the invention, a mandrel and temporary casing are positioned with their lower ends seated on a boot, said casing generally, although not necessarily, being cylindrical and surrounding the mandrel in spaced apart relationship, thereby providing an annular cavity for the reception of the concrete mix. In accordance with the method of the invention, with the mandrel and its surrounding casing resting on the boot, concrete mix in the wet condition is introduced into the annular space between the mandrel and casing, and the mandrel and casing are driven downwardly into the earth with theconcrete in the wet or fluid condition until the boot has reached the desired depth or a firm footing. It should be understood that all references hereinafter to driving with the concrete in the wet conditioncontemplate pouring that concrete not only prior to driving but also during or simultaneously with driving. The casing may then be pulled out and the concrete surrounding the mandrel allowed to set. If desired, as mentioned above, the ini tial heavy upward pulling force required to free the casing may be applied in such fashion that a corresponding downward reactive force will be delivered directly to the boot or pile point via the mandrel, thereby providing a pretest of the load bearing capacity of said pile point. The mandrel is left in position until the concrete mix has set sufliciently to withstand the elastic compression forces of the soil without crumbling, and then withdrawn. In

order to hasten the setting of the concrete shell, the inn...

of equipment in that as soon as the outer casing has been I pulled from the first shell stormed on a job, it may be swung in the leads of a conventional pile driving hammer I to the location of the next pile to be formed, seated on a one-half to three-quarters of its ultimately desired distance in the, ground, and only then the mandrel withdrawn from the preceding formed shell and dropped into position within the partially driven casing, concretein the wet condition positioned between casing and mandrel,

and the mandrel, casing and boot then driven the remain ing distance to the desired depth in the ground. Besides being a substantial time saver, this method avoids the need of providing expensive and cumbersome pile driver leads of such exceptional length as would permit the casing to be held high enough above the ground to permit insertion of the lengthy mandrel therewithin (i.e., socalled fshellingup), the same being unnecessary since the casing may be partially driven alone and the mandrel afterwards dropped therein as described above. A concrete shell formed in accordance with the invention will be characterized by high strength and durability because the wet mix forming the same was originally tightly compacted due to the agitation or shaking of said wet mix by the hammer blows during driving. Thus a dense concrete shell is provided Such a shell has great advantages, especially when, as is usually the case, several piles are driven in closely adjacent positions. For if a shell is not strongly set, the driving of closely adjacent piles will develop a lateral stress that will deform the 7 green concrete, resulting in a distortion or cut-ofi of the shell, thereby vi-tiating its carrying capacity. These dense Inthe drawings:

FIG. 1 is a vertical sectional view, partly broken away, of an apparatus usable in carrying out the method of the invention in one of its aspects, showing a hollowm-andrel and surrounding casing in place on a boot prior to driving and a gravity feed hopper in position at the top of the casing to permit introduction of the concrete mix as shown;

FIG. 1a is a fragmentary vertical sectional view, illustrating a boot construction alternative to that shown in FIG. 1;

FIG. 2 is a vertical sectional view partly broken away of the apparatus of FIG. 1, but with the feed hopper reconcrete shells with the mandrel remaining in place in V sure against the possibility of this disastrous action.

under pressure to fill the void left by the removal of said casing. According to another embodiment of the invention, an extremely thin outer casing may be left permanently around the exterior of the concrete shell in order to protect same. According to still another embodiment of the invention, an extremely thin inner corrugated casing may be provided in close hugging relationship around the mandrel, and the same may be attached to the boot so as to remain in position centrally of the concrete shell, thereby providing'an absolutely watertight interior' for receiving the concrete mix of the pile itself. 7

Furthermore, when desired, the concrete shells of this invention mayform the top section of a multisection pile shell wherein there would be attached to their lower end a conventional pipe, step tapered, standard tapered,

V or straight-sided cylindrical metal pile shell, the upper section of H-beam or other'design, thereby forming a '7 invention.

moved and a driving head attached, showing the same driven into position in the ground; 7

FIG. 2a is a vertical sectional view, partly broken away showing one form ofapparatns for initially breaking the casing tree from the ground and simultaneously pretesting the pile point load bearing capacity;

FIG. 2b is a View similar to FIG. 2a, but showing an-. other embodiment of the casing lifting and pile point load testing device;

FIG. 3 is a view similar to FIG. 2 but showing the casing as it is being pulled out of the ground;

FIG. 4 is a view similar to FIG. 3 showing the remaining parts of the assembly after the casing has been removed, the hollow mandrel being shown in cross-section;

FIG. 5 is a vertical sectional view partly broken away of the completed concrete pile fabricated in accordance with the method of the invention;

FIG. 6 isa View similar to FIG. 1 but showing an apparatus capable of forming a concrete pile shell according to an alternative embodiment of the invention, said pile shell having an extremely thinmetal outer protective liner;

FIG. 7 is a vertical sectional view partly broken away of the; apparatus of FIG. 6, but with the feed hopper removed and a driving head attached, showing the same driven into the ground, the thin protective liner being positioned within the casing;

FIG. 7a is a view similar to FIG. 7, but showing a slightly modified arrangement of the thin protective liner,

thesame being positioned outside the casing;

FIG. 8 is ,a View of the arrangement of FIG. 7 but showing the casing removed and a layer of grout intro but. showing an apparatus capable of forming a concrete pile shellv according to still another alternative embodiment of the invention, said pile shell having an extremely thin corrugated metal inner protective liner;

FIG. 11 is a verticalsectional view partly broken away of the apparatus of FIG. 10, but with theteed hopper removed and a driving head attached, showing the same being driven into the ground;

, FIG. 12 is a view similar to FIG. 11 but showing the casing as it is being pulled;

FIG. 13 is-a vertical sectional view partly broken away of a completed cast-inplace concrete pile fabricated in accordance with the method shown in FIGS. 10-12;-

FIG. 14 is a vertical sectional view 'of an apparatus capable of forming a composite pile shell having'a top concrete section and lower metal sections; and

FIG. 15 is a vertical sectional view similar to FIG. 14

but showing the concrete top section of the shell as formed;

FIG. 16 is a'ver-tical sectional viewof an apparatus capable of forming an alternative embodiment of composite pile shell; and

FIG. 17 is a view similar to FIG. 12, but showing a slightly modified apparatus.

Referring now in more detail to the drawings and particularly to FIGS. 1-5 thereof, a cast-in-place concrete pile 243 having a protective concrete shell 21 is formed in accordance with one aspect of the invention as follows. A boot or shell point 22 of conventional design is provided and a casing 23 may be positioned as shown on said boot with its lower end resting or seated on a circumferential shoulder 24 formed thereon. With the casing and boot either resting on the ground surface or driven partially into the ground, a hollow mandrel 25 having centering lugs 26 may be lowered down within casing 23 until its lower end comes to rest or seats on boot 22. As shown this mandrel may be, although not necessarily, tapered slightly from topto bottom and is dimensioned relative to casing 23 so as to provide an annular space 27 therebetween, said space being of a size equivalent to the desired thickness of the concrete shell which is to be cast. Although as shown the boots shoulder 2'4 and the maniirels centering lugs 26 serve to maintain the mandrel and casing in the desired fixed spaced apart relationship so as to insure the presence of annular space 27, it will be of course understood that various other obvious alter-' natives may be employed to accomplish this purpose. With the apparatus assembled, a gravity feed type hopper 28 having a coned center 29 may be positioned at the top of the mandrel and casing and by means of the same a concrete mix 30 in the wet condition is fed down into of the mast is provided with a T-head 201. The lower 25, as shown at 29-2, in 'orderto make the mast stable, but alternatively the top of the mandrel could project into a suitable socket formed in the bottom of the mast to achieve the same stabiltiy effect. A shoulder 2% formed on the mast bears against the upper end of the mandrel and cables 2%, 205 running between pairs of fall blocks 2%, 207, secured by suitable links, respec- 1 tively, to the masts T-head and the upper end of the casing transmit the pulling force. The upper ends of cables 20 4, 205 run over suitable fair-leaders to drums on the'hoisting engine of the pile driver (not shown). Of course, conventional cross-over sheaves could be employed so as to run a single cable to a single hoisting drum.

In operation, SllfilClElIlt lifting force is applied to cables 264, 205 which serves to free the casing 23 and pull same up a short distance out of the ground, say for example, 10 to 12 feet. Since the application of this force will cause an equal reaction downward upon the mandrel through the medium of mast 200, suchdownward reaction would, of course, be applied directly against the pile point 22, and thus the pile point will be pro-tested to the extent of the force of the pull exerted by the pulling mast. After this initial pull upward on the casing,

I the mast 200 may be removed by any convenient means the space 27. Prior to thus assembling the aforementioned parts, a sleeve 31 can be driven by hand sledge or other conventional means into the ground and the boot 22 positioned therewithin as shown. Alternatively to the boot construction shown in FIG. 1', there may be employed, as shown in FIG. 1a, a flat boot pl-ate 22a having three or more upstanding tapered guide lugs 22b, adapted to center the mandrel relative to the casing, and a ring 23a secured to the lower end of the casing and adapted to receive said boot plate as shown.

Thereafter as shown in FIG. 2, the feed hopper 28 may be removed from the casing and a driving head 32 secured by means of a pin 33 to both the casing23 and the mandrel 25. Thereupon the mandrel and casing are driven into the earth by means of impact blows delivered to the driving head by a conventional pile hammer. It will be understood if desired such blows may be delivered directly to the casing and mandrel, but in any event since the concrete mix 30 is still in the wet condition during this driving action, the same will be jolted and shaken or agitated due to the impacts and will therefore settle and become tightly compacted, thus eliminating air pockets and weak areas and insuring the formation upon setting of a strong and durable and watertight concrete shell.

When the boot 22 has been driven to the desired depth, the driving head is removed and casing 23 pulled upwardly from the ground. If desired, the initial heavy upward pull on the casing may be applied in such fashion that a corresponding downward reactive force will be delivered directly to the pile point via the mandrel 25. The utilization of this principle not only serves to break the casing free from the ground but also, since the reactive force involved will be quite large, serves to prevent any upward displacement of the pile point and simultaneously to pre-test the load bearing capacity of the pile point, Quite obviously, many lift devices of varying design may be employed to carry out this step, all using the basic reaction principle involved. For purposes of illustration, two specific embodiments of such devices are shown in FIGS. 2(a) and 2(b).

In the embodiment shown in FIG. 2(a), the lift device comprises a mast 200, which may, for example, be in the order of about 12 feet. As shown, the upper end such as by hooking into its yolk 208. Thereafter the casing may be pulled completely out of the ground by any conventional hoist means as shown in FIG. 3.

The lift mechanism 210 shown in FIG. 2(1)) performs in similar fashion but embodies a hydraulic mast, comprising a hydraulic piston and cylinder assembly 211, 212, with the piston having an internal conduit 213 for delivering fluid under pressure to cylinder 212. A crosshead 214 is provided at the upper end of the piston and may be secured by suitable links to the upper end of casing 23. The cylinder 212 nests within hollow mandrel 25 and is provided with an annular shoulder 215 bearing against the upper end of the mandrel and tie signed to transmit the downward reactive force directly to the pile point via the mandrel. Introduction of fluid under pressure into the cylinder 212 will cause the piston and its orosshead to raise, thereby freeing the casing and giving same its initial lift upward, while a downward reaction is applied through shoulder 215 to the mandrel and via the latter transmitted directly to the pile point, thereby pre-testing the pile point to the extent of the load applied. This hydraulic embodiment is, of course, desirable when a source of hydraulic pressure is available, such as is the case when a hydraulic hammer is being used on the job. After this initial pull, the lift mechanism 210 is removed and the casing 23 completely pulled out as shown in FIG. 3.

Quite obviously, with either the embodiment of FIG.

said. Such force will of course vary depending on the length of the casing and the type of the ground in which it is driven. Generally speaking, however, it ordinarily requires 40 to 50 tons to free the casing, and thus such a method pre-tests the pile point for that amount, which is a very satisfactory pre-test. that on any particular job site, it would be easy to determine the exact force exerted by the pulling mast, and this calculation would then establish the load as to which each pile point had been pre-tested. In the case of the hydraulic embodiment of FIG. 2(b), such amount could be readily established by measuring the hydraulic fluid pressure required to free the casing. Likewise, in the case of the embodiment of FIG. 2(a), known means are available for measuring the tension in cables under load. It should be understood that the use of such lift-mechanisms which react against the mandrel also insure that the mandrel will not pull loose while the casing is being it should be understood mentioned US. Patent No. 2,421,666. mandrel may be provided with a steam line 37 and a cold removed, which is desirable since any movement of the mandrel at that time might allow the concrete shell to I partially collapse. Moreover, since this reactive force is delivered directly to the pile point or boot during removal of the casing, it serves the very desirable purpose of preventing that pile point from rising even slightly in the ground. Quite obviously, even the slightest upwardmovej mentof the pile point is highly disadvantageous, since subsequent loading of the pile will result in the down ward movement of the point to its former location, there= by causing a corresponding settling of the building or other structure supported. It should be understood that this casing removal and pile point pre-testing aspect of the invention may also be used in conjunction with other pile shell formation processes wherein. the concrete may i be poured after complete driving of the casing.

-23 comes into position for immediate driving or another pile shell. This means that by having a pluralityof .hol low mandrels on the job site a second closely adjacent pile shell may be driven while the first pile shell is hardem ing, thereby increasing the speed of operation.

may simply be positioned on another boot, driven partially intothe ground at the next pile location, and the same mandrehafter being removed from the first shell dropped therein. Such removal of the casing will, of course, tend toleave a slight circumferential space between the outer walls of the concrete mix 39 and the ground. Of course,

normal elastic compression of the soil will tend to close in this void, but in order to insure that the concrete mix comes into close gripping relationship with the ground,

a vibrator 34 of conventional design may be provided in the lower interior of mandrel 25, the same being connected by line 35 with any suitable source of electric energy and adapted to be energized when the casing 23- is being removed from the ground. Alternatively, if desired, one or more vibrators 340 connected by lines 35a to a power source may be hung from casing 23 and actually positioned in the concrete in the space between mandrel and easing, the same being drawn up through the wet concrete mix as the casing is pulled.- Such vibrators will cause'the mix 31} to be agitated, thereby urging the still unset particles thereof radially outwardly into close gripping contact with the ground as shown at 36. Similarly, if desired, the vibration can be accomplished by the use of the driving hammer during the period while the exter'ior casing 23 is being removed, Alternatively, this circumferential spacer maybe filled bythetintrodnction' of grout under pressure as described in more detailbelow V in connection with the embodiment of FIGS. 6-9.

Turning now to FIG. 4, after the casing 23 has been 7 completely removed, the concrete may be leveled flush at the top of sleeve 31 and then allowed to setsufliciently' to Withstand ground pressures, such setting, if desired,

being hastened by applying heat to the mix from the interior of mandrel 25. Although shown rather schematically, it should be understood that this mandrel 25 .may for example be generally similar in construction and operating function to the hollow form 18 of the above- As shown, the

' ficiently, the interior of rthe mandrel may be cooled, for

example by admitting cold water-through line 38. Such A cooling will tend to contract the metal mandrel, there- Al'ter: natively, as described above, after being pulled the casing upon facilitating removal from the newly formed con crete pile shell 21. As mentioned above, the mandrel maybe, although not necessarily, downwardly tapered to make its removal easier, and moreover, the same may be provided with an internal hammer, as wellas jack.- ing equipment (not shown) after the fashion of form 18 in the aforesaid Patent No. 2,421,666. Then when it isdesired to remove the mandrel, jacking pressure may be applied downwardly upon the concrete shell and, it necessary, at the same timehammer blows may be delivered upwardly against the mandrel itself as described in that prior patent; It should also be understood that if desired the mandrel could be made of the collapsible type so as to facilitate removal thereof.

As shown in FIG. 5, after removal of the mandrel a concrete pile shell 21 has been formed, and it will be observed that such a pile shell does not require the presence of any metal whatsoever remaining in the ground. Nevertheless, a plurality of such shells 21 may 7 be driven in closely adjacent locations and then before the actual pouring of the concrete into the interior thereof so as to complete cast-in-place piles, the shell interiors maybe inspected and the fact of a perfect pile verified; prior to filling the pile itself. Moreover, by pulling the casing, as described above, while reacting downwardly on the pile point, each such pile point may be pre-tested for load bearing capacity prior to fillingthe pile itself. Referring now to FIGS. 6-9, an alternative embodiment of the method is therein portrayed. This alternative em-,

bodiment is basically similar to the method described above in connection with FIGS. 1-5 except that it results in the production of a concrete pile shell having an extremelythin metal, outer protective liner 40 which embraces the outer surfaceof a concrete shell 41 and is designed to prevent deterioration of said shell as a result of underground waters or impacts from the driving of adjacent piles. Such a metal shelldtl being Water proof will serve to protect the concrete shell from such deterioration, and nevertheless because of the method of installing such shell, this liner may be formed of extremely thin or light gage metal, thereby keeping to a minimum the amount of steel used. As mentioned above, in the now conventional steel shell type, cast-in-place concrete piles, the shell is first driven by itself into the ground and as such must be capable in and of itself of sustaining the elastic compression forces of the soil. Experience has shown that sucha shell to be satisfactory must be made of about 16 gage or more steel, which is approximately ,5 thickness. On the other hand, by forming the pile shell as shown 'in FIGS. 6-9 hereof and as will be pointed out in detail hereinafter, the protective metal outer liner 4% need not be capable of sustaining ordinary elastic compresison of the soil and may, therefore, be formed of 20-24 gage steel or, in other words, or less in thick ness. Thus by driving a concreteshell in accordance with the method hereof while the concrete is in the wet condition, a thin protective liner maybe provided, thereby with a saving of 50% 'or'more of the steel involved in conventional steel pile shells.

As mentioned above, the method illustrated in FIGS.

6-9 follows closely that described in connection with FIGS. 1-5 above. Thus a casing 42 with a tapered'hollow mandrel 43 disposed therewithin is positioned on a boot or piled-4. The thin metal outer protective liner or shell 4%? may be interposed between the mandrel and casing 42 and is dimensioned so its diameter is sufficiently smaller than the inner diameter of casing 42 to permit ready removal of the latter after driving. In some cases, if preferred, as described below, the liner 40 may be positioned outside the casing 42 instead'of inside. With the parts in position as shown in FIG. 6, concrete mix 45 in the wet condition is fed downfrom a hopper 46 and positioned between the mandrel and casing in the space between mandrel and liner 45]. With the mix still in the wet condition, the hopper'is removed and a driving head 47 secured to the casing and mandrel and the boot driven into the ground as shown in FIG. 7. Casing 42 is then pulled as indicated in FIG. 8, leaving the outer liner 4% in position surrounding the still wet concrete mix 45. It should be of course understood that, if desired, the casing may be initially freed from the ground and the pile point load capacity pre-tested as described above by use of reaction lift devices such as shown in FIGS. 20 or2b. In order to fill the annular void left by the removal of said casing, a cylindrical column of grout 48 may be formed between the liner and the ground While the casing is being removed, the same being ejected under pressure as from grout pipes 49 disposed around the exterior of casing 42.

Alternately, if desired, the thin metal protective liner may initially be positioned outside the casing. Then as shown in FIGS. 7a and 8a, the thin liner 49a will surround casing 420 and when the casing 42a is being removed, the resulting annular void between the concrete mix and the interior of the liner 4% may be filled with grout injected underpressure, or, if preferred, such space may be filled by vibrating the concrete mix as described above in connection with the embodiment of FIGS. 1-5, so as to urge the still unset particles of mix into close gripping contact with the interior of liner 40a.

At this point the concrete mix 45 is allowed to set sufliciently to withstand ground pressures, this setting being expedited if desired by heating of the mandrel 43 as described above in connection with the mandrel 25 of FIGS. 1-5. Again it should be understood that this mandrel 43 may be constructed and designed to operate in accordance with from 18 of the above-mentioned US. Patent No. 2,421,666. After the mix has been allowed to set, thereby forming the concrete shell 41, both that shell and its outer liner 44) may be cut off at the desired elevation above the ground as at 50, the mandrel 43 may be removed as described above in connection with FIGS. 1-5 and the interior of the shell after inspection thereof, filled with concrete, thereby forming the pile 51.

Turning now to FIGS. -13 hereof, there is portrayed still another alternative embodiment of the invention which provides for the manufacture of a concrete pile shell 60 having an extremely thin, corrugated metal inner liner 61. Once again this liner 61 may be formed of extremely light gage metal (i.e. -24 gage), since it may by itself be incapable of sustaining ordinary elastic compression of the soil as contradistinguished from a conventional steel pile shell which, as described above, must be capable of withstanding such elastic compression. Such an inner corrugated liner 61 will provide substantial watertightness for the interior of the pile shell, thereby insuring that a cast-in-place concrete pile 62 may be formed with absolute protection against deterioration by underground waters.

Once again a hollow mandrel 63 surrounded in spaced relation by metal casing 64 is positioned on a boot or pile point 65' which has been placed within a cylindrical sleeve 66, the latter having been driven into the ground by hand sledge or. otherwise. However, in this embodiment an extremely thin corrugated inner metal liner 61 is positioned so as to closely surround mandrel 63. This liner as mentioned above is provided with helical or plain circumferential corrugations 67 and provides an essentially watertight joint with said boot. The lower end of the corrugated liner may be screwed into the boot as shown at 68. If desired, this liner 61 may be formed of a plurality of helically corrugated sections which are screwed together.

Once again after the concrete mix 69 in the wet condition delivered from a feed hopper 70 has been positioned between the casing and mandrel in the spacebetween liner and mandrel, the hopper is removed and the assembly driven into the ground as shown in FIG. 11. T hereupon casing 64 is pulled as shown in FIG. 12, it being again of course understood that the casing may be initially freed from the ground and the pile point load bearing capacity pre-tested as described above by use of reaction lift devices such as shown in FIG. 2a or 2b. Such removal of the casing 64 will again cause a space to be formed beground. Or in the alternative, grout may be introduced by suitable means as described above so as to fill the void between the ground and the concrete mix.

The concrete mix is then leveled flush with the top of sleeve 66 as shown at '71. The concrete is then allowed to set sufficiently to withstand ground pressures and once again if desired, means may be provided to heat the interior of mandrel 63 to expedite this setting. However, it should be observed that in this embodiment the mandrel 63 may be straight sided and need not be tapered, noris it necessary that any hammer or external jacking apparatus be providedfor removal of the same; Thus after the concrete has set, the sleeve 66 may be removed'from the ground, and mandrel 63 may be pulled upwardly out of contact with the interior of the corrugated shell 61; It will be understood that the corrugations in said shell permit the passage of air between the. same and the outer walls of the mandrel, thereby eliminating the formation of suctional forces and permitting ready removal of the mandrel. Once the mandrel has been removed, the inner lining 61 may be cut off at the desired level as shown at 72. Thereafter following inspection of the interior of the pile shell, the concrete pile 62 may be cast in place.

When concrete pile shells as described hereinabove constitute in and of themselves the entire pile shell, the length of such a shell will naturally be limited because it is necessary in the formation thereof to pull the outside casing upwardly out of the ground after the shell has been driven, and such pulling of a casing becomes a most difficult problem when the length of the shell is excessive. However, in certain driving locations it may be necessary to provide a rather lengthy shell so as to reach a bearing stratawhich is suitable for the loads anticipated, and it may be desirable to provide a composite shell wherein the upper section is formed of concrete as described hereinabove and the lower sections are formed of metal. The use of concrete in such an upper shell section is especially desirable, since in a tapered pile shell the upper section naturally has the greatest diameter and from an economic standpoint, a steel shell is not very satisfactory for diameters over 18 inches, since at such sizes the metal shell must be made so heavy to withstand ground pressures that its cost becomes noncompetitive. Turning therefore to FIGS. 14 and 15, it will be seen that a composite pile shell having an upper concrete section 81 formed as hereinabove described and lower metal sections 82, 83 can readily be formed. Lower metal sections 82 may be of the plain pipe type or of the conventional step taper type as disclosed in M. M. Upson Patent No. 1,836,140, or of the straight sided, cylindrical type, while the lowermost section 83 may, if desired, comprise a heavy taper shell point formed of light gage steel in accordance with the teaching of copending Herman R. Smith patent application Serial No. 455,610, filed September 13, 1954. Of course, it should be understood that the lowermost section of this composite pile need not be of this heavy taper shell point type, but rather could equally well be of convventional step taper or straight sided cylindrical design. For driving this composite shell there may be provided a conventional, noncollapsible step taper core or mandrel 84 having an upper cylindrical section '85 which corresponds, for example to the hollow mandrel 6-3 in FIG. 10. The lower end of this core section 85 driveson a heavy driving ring 86 which has been substituted for the boot a 11 ring of the previous figures. Welded or otherwise secured to the upper surface of this driving ring is a thin corrugatedmetal inner liner 87 similar to liner 61 in FIG. l0, and surrounding this liner in spaced relationship there to'fis a cylindrical casing 38 similar in design to casing 64 in FIG. 10. To the underside of driving ring 86 is welded'or otherwise secured a standard screw collar 89 which is adapted-to receive in screw threadedrelatioru' ship the upper end of metal shell section 82. i In operation mandrel 84 may be inserted as shown within shell sections 81, 82 and 83, wet concrete mix positioned between mandrel and casing in the space between liner 87 and casing 88, a driving head attached and the assembly then driven into the earth by a conventional pile hammer. Or on the other hand, the composite pile of this embodiment may be formed by first driving into the ground the casing and the lower metal shell sections a with the core disposed therewithin and then pouring the concrete mix into the space between the casing and core. Of course, the inner liner'd? being of extremely thin metal is, as has been discussed above, incapable in and of itself of withstanding ground pressures and therefore after the shell has thus been driven inorder to prevent buckling ofthisliner, the core 34 would be left in place until the concrete shell section 81 has's'et sufficiently to withstand the. ground pressures involved. However, cores such as 84 are expensiv'e'pieces of equipment, and it is therefore undesirable to have them remain idle for any lengthy period of time, and therefore an auxiliary stiffener shell 91 may be provided between the liner 87 and the upper section 85 of the core. Then asshown in FIG. 15, the core may be withdrawn even before the concrete has been allowed to set, with the auxiliary stiffener shell 91 being left in place, and this auxiliary shell provides the necessary strength and rigidity to withstand ground pres sures, thus preventing buckling of the liner 87. It'should be understood that if it is desired to react downwardly on the pile point while removing the casing in this em-v bodiment as described above in connection with PIGS. 2(a) and 2(1)), the casing should be pulled prior to this removal of core 84, with the downward reactive force be ing delivered to the point through said core 84. On the other hand, if such downward reactive force is not cont'emplated, the casing'may be pulled either before or after When'the concrete has set .suhiremoval of core 84. ciently, the auxiliary shell 91 may be withdrawn, and inner liner 87 cut off at the desired level. Such an auxiliary stiffener shell is of course a much less expensive item than the core 84 and therefore permits of more economical operation. By the foregoing a composite concrete-metal pile shell has been formed wherein the upper concrete section is provided with an extremely thin corrugated metal inner liner 87, or in other words similar to the embodiment of FIG. 13. Of course, it should be understood that such a composite concrete-metal shell could also be formed wherein the top concrete section thereof was similar to the shell of FIG. 5 having no metal liner or similar to the shell of FIG. 9 having an extremely thin metal outer liner. In either of these latter cases it should be of course understood that the upper section 105 of the core would preferably be of slightly metal pipe section. Thus in'FIG., 16 there is shown an apparatus driven into the ground capable of forming such a composite shell and Qcomprising mandrel 93, surrounding spaced casing 94, driving head 95, with concrete 96 positioned therebetween for forming the upper concrete shell section. Thelower ends ofboth'casing and manl2 drel are seated on a heavy driving ring 97 which has been substituted for the boot of FIGS. 1-5. Ring 97 may be provided with a downwardly tapered lip 98 to which there may be secured by a wedge fit a section of a metal pipe 99, closed off in watertight fashion at its lower end by a plate 10%, which forms the lower metal shell section. In operation this apparatus may be driven into the ground as a unit or the pipe 99 driven partially by itself and the mandrel 93 and casing 97 then positioned as shown thereabove and the apparatus driven the remaining distance into the ground, casing 94 pulled, concrete $6 allowed toset and the mandrel 93 removed. Vibration of the concrete 96 to fill up any void which may be left on removal of the casing may of course be employed, or grouting if desired, all as described above. It will be understood that upon completion of driving and after removal of the mandrel, the interior of the upper concrete section and lower metal pipe section are filled with concrete, thereby completing the pile. Sometimes in the driving of such composite piles wherein the lower pipe section is of considerable length or heavy ground resistance to driving is expected from rock formations and the like,'it may be desirable to provide a driving core extending through'the upper concrete section and-through at least apart of the lower pipe section so as to strengthen the latter during driving and prevent bending of the pipe. Such an apparatus is shown in FIG. 17 comprising a mandrel or core 103, surrounding spaced casing 104, driving head 1195, concrete 106 positioned between core and casing for forming the upper concrete shell section, driving ring 1 07, and lower metal pipe section 108,, the latter being closed oif at its lower end in watertight fashion by plate. The functioning and operation of this apparatus is the same as that described in connection with FIG. 16 and forms a composite concrete-metal shell of the same type, the only diiference being that core or mandrel 103 extends through the upper concrete section down through driving ring 107 and at least partially into the lower pipe section 108 as shown at 111, thereby serving to reinforce and strengthen said vent bending thereof during driving.

Although certain particular embodiments of the invention are herein disclosed for purposes of explanation,

pipe section and prevarious further modifications thereof after study of this specification will be apparent to those skilled in the art to which this invention pertains. Reference should accordingly be hadto the appended claims to determine the scope of. the invention.

What is claimed and desired to be secured byLetters Patent is: V

l. A method of forming a hollow concrete pile shell which comprises the steps of seating a mandrel and a surrounding casing spaced therefrom on a pile point, positioning concrete mix in the Wet condition between the mandrel and casing and driving said mandrel, casing and pile point in the ground, applying an upward force to the casing so as to remove same prior to setting of the concrete and simultaneously delivering the corresponding downward reactive force directly to the pile point via the mandrel, thereby .pre-testing the load bearing capacity of the pile point and preventing any upward dislodgment of said point during removal of the casing and removing said mandrel after the concrete has set sufliciently to withstand ground pressures.

2. A method of morming a hollow concrete pile shell which comprises the steps of seating a mandrel and a surrounding casing spaced therefrom on a pile point, positioning concrete mix between the mandrel and casing and driving said mandrel and casing and pile point in the ground, -applying 'a heavy upward pull on the casing while reacting downward on the mandrel so as to free the casing prior to setting of, the concrete and simulpoint, and removing the mandrel.

3. A method of forming a hollow concrete pile shell having a thin metal outer protective liner which is too thin safely to withstand by itself the normal elastic compressive forces of the surrounding soil, which method comprises the steps of providing a hollow mandrel and a surrounding casing spaced therefrom and resting on a boot with the thin cylindrical metal outer liner positioned between the mandrel and easing, said liner being spaced from the mandrel, driving said elements in the ground, a quantity of concrete mix in the wet condition being positioned therebetween, applying an upward force to the casing so as to remove same prior to setting of the concrete with the liner remaining in the ground, and delivering the corresponding downward reactive force directly to the pile point through the mandrel, thereby pre-testing the load bearing capacity of the pile point and preventing an upward dislodgment thereof during removal of the casing and then removing said mandrel after the concrete has set sufficiently to withstand ground pressures.

4. A method of forming a hollow concrete pile shell which comprises the steps of providing a mandrel and a surrounding casing resting on a boot with a thin corrugated metal inner shell liner positioned between the mandrel and casing and being spaced from the casing, driving said elements in the ground, a quantity of concrete mix in the wet condition being positioned. therebetween, applying an upward force to the casing so as to remove same prior to setting of the concrete with the liner remaining in the ground, and delivering the corresponding downward reactive force directly to the pile point through the mandrel, thereby pre-testing the load bearing capacity of the pile point and preventing an upward dislodgment thereof during removal of the casing and then removing said mandrel after the concrete has set sufiiciently to withstand ground pressures.

5. Method of forming a hollow concrete pile shell in the earth, which comprises the steps of assembling on a boot, a mandrel shaped to form the predetermined desired interior cavity of the shell, together with a surrounding casing spaced from the mandrel; driving such assembly of elements into the earth, a mass of concrete mix in the wet condition being introduced at a time while said mandrel, casing and boot are maintained in their assembled relationship into the space in the casing surrounding said mandrel; pulling the casing from the earth before the mix has set; and, after the mix has set, removing the mandrel.

6. A method of forming a hollow concrete pile shell which comprises the steps of providing boot means, resting the lower surface of a mandrel and a casing on said boot means, said casing surrounding said mandrel and being spaced therefrom, introducing a quantity of concrete mix in the wet condition to the space between said mandrel and casing, driving said mandrel, casing and boot means in the ground while the miX is still in the wet condition, said driving tightly compacting said mix, pulling the casing before the mix has set, allowing the mix to set and removing the mandrel.

7. A method of forming a hollow concrete pile shell having a thin metal outer protective liner which is too thin safely to withstand by itself the normal elastic compressive forces of the surrounding soil, which method comprises the steps of providing boot means, resting the lower surfaces of a hollow mandrel, a thin cylindrical metal outer liner and a casing surrounding said liner on said boot means with the thin cylindrical metal outer liner positioned between the mandrel and casing and adjacent the inner surface of the casing, said liner being spaced from the mandrel, introducing a quantity of concrete mix in the wet condition to the space between said mandrel and liner, driving said mandrel, liner, casing and boot means in the ground while the mix is still in the wet condition, said driving tightly compacting said mix then before the mix has set pulling the casing with the liner 14 remaining in the ground, allowing the mix to set and removing the mandrel.

8. A method of forming a hollow concrete pile shell which comprises the steps of providing boot means, resting the lower surfaces of a mandrel and a surrounding casing on said boot means with a thin corrugated metal inner'shell liner positioned between the mandrel and casing, said liner being spaced from the casing to lie adjacent the outer surface of said mandrel, introducing a quantity of concrete mix in the wet condition to the space between said inner liner and casing, driving said mandrel, liner, casing and boot means in the ground while the mix is still in the wet condition, said driving tightly compacting said mix, pulling the casing before the mix has set with the liner remaining in the ground, allowing the mix to set and removing the mandrel.

9. A method of forming a hollow cylindrical, concrete pile shell which comprises the steps of providing boot means, resting the lower surfaces of a cylindrical mandrel and a surrounding, circumferentially spaced, cylindrical casing on said boot means, introducing a quantity of concrete mix in the wet condition to the annular space between said mandrel and casing, driving said mandrel,

casing and said boot means in theground while the mix is still in the wet condition, said driving tightly compacting said mix, pulling the casing before the mix has set, vibrating saidmandrel so as to agitate said mix and urge the particles thereof radially outwardly into the space left by the removal of the casing, allowing the mix to set and removing the mandrel.

10. A method of forming. a composite concrete-metal pile shell which comprises providing at least one lower metal shell section, securing the lower end of an annular driving ring to the upper end of said metal section, said annular driving ring having seat means formed on its upper end, resting a temporary protective shell and a casing surrounding said shell on said seat means on the upper surface of said ring, said casing and protective shell being so positioned as to form a space therebetween, inserting a core within said sections, the core having an upper section adjacent the inner surface of said protective shell, introducing a quantity of concrete into the space between said shell and casing, driving said elements in the ground, removing said casing andcore, allowing the concrete to set and then removing said protective shell.

11. A method of forming a composite concrete-metal pile shell which comprises providing at least one lower metal shell section, securing the lower end of an annular driving ring to the upper end of said metal shell section, said annular driving ring having seat means formed on its upper end, resting a hollow casing on said seat means, inserting a core within said sections, the core having an upper section resting on said driving ring and so positioned relatively to said casing as to provide a space therebetween extending upwardly from the upper surface of said driving ring, introducing a quantity of concrete into the space between core and easing, driving said elements in the ground and pulling said casing, allowing the concrete to set and removing said core. I

12. A method of forming a hollow concrete pile shell having a thin metal protective liner which is too thin safely to withstand by itself the normal elastic compressive forces of the surrounding soil, which method comprises the steps of providing a mandrel, a thin tubular liner spaced from said mandrel and a casing surrounding said liner all resting on a boot, introducing a quantity of concrete mix in the wet condition between the mandrel and easing, driving the mandrel, liner and casing in the ground while the mix is still in the wet condition, said driving tightly compacting said mix, pulling the casing before the mix has set, with the liner remaining in the ground, allowing the mix to set and removing the mandrel. 13. A method of forming a concrete pile shell which comprises assembling a boot formed with seat means, a

hollow mandrel resting on said boot and a casing surrounding said mandrel and seated on said seat means,

said boot, mandrel and ca'sing Being so positioned relatively to each other as to provide a space between said mandrel -and casing and extending upwardly of said boot,

introducing a quantity of concrete mix into the space between said casing and mandrel, driving said assembly in the ground, removing the casing before the mix has 7 set, allowing the mix to set, and then'removing the to from within said hollow mandrel.

References Cited in the file of this hatent UNITED STATES PATENTS Shuman Ian. 10, 190 5 Ridley Dec. 15, 1914 15 Prnyn Aug. 13, 1918 Cortes June16, 1925 Weight Apr. 13, 1926 Hiley 'May24, 1927 Newton Jan. 7, 1930 Upson May 31, 1932 Upson July 5, 1932 Frankignoul Aug. 16, 1932 Watt Oct. 4, 1932 Stem 'Oct. 23, 1934 Takechi July 16, 1935 Watt Aug. 4, 1936 Upson et a1. June 3, 1947 Upson et a1 Mar. 30, 1948 Holmes June 27, 1950 UNITED STATES PATENT OFFICE CE'RTIFICATE OF CURRECTION Patent No.'3,034,304 May 15, 1962 Maxwell M. Upson It is hereby certified that error appears in the above numbered patent requiring correction and that the said Letters Patent should read as corrected below.

Column 1, line 30, for "pipe" read pile line 47,. strike out "on"; column 2, line 6, for "above-desicribed" read above-described column 5, line 28, after "apparatus" 1n sert thus column 8, line 64, after "pile" insert polnt column 9, line 32, for "from" read form line 56, after "by" insert a column 12, line 65, for "morming" read forming Signed and sealed this 4th day of September 1962.

(SEAL) Attest:

DAVID L. LADD Commissioner of Patents ERNEST W. SWIDER Attesting Officer 

